//main.cpp
#include "Subject.h" 
#include "Observer.h"
#include <iostream> 
using namespace std;

int main(int argc,char* argv[]) 
{ 
	ConcreteSubject* sub = new ConcreteSubject();
	Observer* o1 = new ConcreteObserverA(sub);
	Observer* o2 = new ConcreteObserverB(sub);
	sub->SetState("old");
	sub->Notify();
	sub->SetState("new"); //也可以由Observer调用
	sub->Notify();
	return 0; 
}